Sienna Miller is rumoured to be playing Mark Ruffalo's wife in Foxcatcher

Sienna Miller has reportedly joined the cast of upcoming drama Foxcatcher.

The Factory Girl actress - who welcomed her first child, daughter Marlowe, in July - will play the wife of tragic Olympic wrestler Dave Schultz in the film, which is based on a true story, according to Deadline.

Mark Ruffalo is set to play Schultz, while Channing Tatum will star as his brother.

Steve Carell is tipped to play John du Pont, heir to the du Pont chemical fortune, who built a wrestling training centre called Team Foxcatcher. He shot and killed his friend Schultz during an attack of paranoid schizophrenia.